JP5962424B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly, to a locking structure of an external gear for rotationally driving a developing sleeve and other cylindrical members that are constituent members of the image forming apparatus.

  Many of the developing devices used in electrophotographic image forming apparatuses, for example, copiers, have a developing sleeve (nonmagnetic material) that is a cylindrical member, a part of which is composed of toner and a magnetic carrier. The developing sleeve is rotatably held in a state where it is exposed from the housing containing the developer, and the developing sleeve is arranged so as to face the photosensitive drum at the exposed portion.

Then, by rotating the developing sleeve, the developer is developed by cooperating with the enclosing magnet roller and conveying the developer planted in the form of a magnetic brush on the surface of the developing sleeve from the housing to the photosensitive drum. Yes.
The developing sleeve is rotationally driven by power transmitted from a rotational power source such as a motor via a power transmission mechanism. In this case, there is known one in which an external gear is externally fitted to the developing sleeve to constitute the final stage of the power transmission mechanism (Patent Document 1).

FIG. 10 shows a locking structure of the external gear 206 to the developing sleeve 200 disclosed in Patent Document 1. The external gear of Patent Document 1 is an external gear 206 with a boss, and the boss portion 204 is provided with a through-hole 204A opened in the radial direction. On the other hand, the developing sleeve 200 is formed with a female screw (hereinafter referred to as “screw hole 200 </ b> A”) penetrating in the radial direction.
Then, the external gear 206 is extrapolated to the developing sleeve 200 and aligned so that the screw hole 200A and the through hole 204A overlap, and then the screw 208 is inserted from the through hole 204A and screwed into the screw hole 200A. The external gear 206 is locked to the developing sleeve 200.

  Then, another external gear (not shown) to which power from the rotational power source is transmitted meshes with the gear portion 202, and the rotational power of the other external gear is transmitted via the external gear 206 and the screw 208. This is transmitted to the developing sleeve 200, and the developing sleeve 200 is rotated.

JP 2001-312142 A Japanese Patent Laid-Open No. 10-142936

  However, the thickness of the developing sleeve 200 is generally 0 in order to reduce the radial distance from the outer peripheral surface of the magnet roller to the outer peripheral surface of the developing sleeve 200 as much as possible to ensure a sufficient magnetic force on the outer peripheral surface of the developing sleeve 200. Since it is as thin as .5 [mm], even if an internal thread is formed on this, the screw allowance is small. In addition, since it is necessary to use a screw with a short pitch in order to increase the number of threads to be engaged, it is limited to a thin screw.

  For this reason, when the rotation start and the rotation stop of the external gear 206 are repeated, the external force received in the circumferential direction from the external gear 206 acts to swing the screw 208 like a pendulum about the screw hole 200A. As a result, when the cumulative operation time of the developing device becomes long, the thread of the screw hole 200A may eventually be crushed and the screw 208 may be dropped, and the rotational power of the external gear 206 may not be transmitted to the developing sleeve 200.

Further, the developing roller 200 needs to be arranged opposite to each other in parallel with each other with a photosensitive drum (not shown) with a narrow gap of, for example, 0.3 [mm], and from the viewpoint of ensuring a degree of design freedom. It is preferable that a rotation protrusion such as the screw head 208A is not provided as much as possible on the outer peripheral side of the screw.
In order to cope with this, a configuration in which a female screw is formed in the boss portion of the external gear, a through hole is formed in the developing sleeve, and the screw head is placed in the developing sleeve by screwing from the inside of the developing sleeve is also conceivable. However, the screw tightening operation from the inside of the developing sleeve having an outer diameter of about 16 [mm] is difficult to withstand.

The above problem is not limited to the case where the external gear is locked to the developing sleeve, but also to the case where the external gear is locked to a fixing roller or a photosensitive drum containing a halogen heater or the like. It is common.
According to the present invention, the external gear can be easily locked to the cylindrical member, and the projection of the outer peripheral side of the cylindrical member can be prevented as much as possible, and the transmission of the rotational power can be maintained. An object of the present invention is to provide an image forming apparatus having a locking structure.

To achieve the above object, an image forming apparatus according to the present invention, lock the extrapolated external gear on the outer circumference of the cylindrical member in the locking means, the cylindrical power of the drive source via the external gear An image forming apparatus configured to transmit to a member and rotationally drive the cylindrical member , wherein at least one engagement hole is formed on an inner peripheral surface of a shaft hole of the external gear, and the cylindrical member , said external gear has a through hole is formed overlapping with the engaging hole of the external gear while being attached to the predetermined position of said cylindrical member, said locking means, said cylindrical inner member An insertion body to be inserted; a locking projection; and a biasing means for biasing the locking projection against the insertion body in the radial direction of the cylindrical member, and configured to rotationally drive the cylindrical member Is extrapolated to the end of the cylindrical member to hold the cylindrical member rotatably. A sliding bearing member made of a synthetic resin having a bottomed cylindrical shape, a plate-like portion provided at the bottom of the sliding bearing member, and an exposure extending from the plate-like portion and exposed to the outside of the cylindrical member A terminal member including a piece portion, a coil spring portion interposed between the insert and the plate-like portion in a compressed state, one end slidingly contacting the plate-like portion, and the other end of the coil spring portion it is extended strands of the coil spring portion, and a voltage application member comprising a resiliently abutting contact portion on the inner peripheral surface of the cylindrical member, interpolating the insert to the cylindrical member when the said locking projection which is biased by the biasing means, through the through hole of the cylindrical member, by engaging said engagement holes of said external gear, the external gear is the a locked structure for a cylindrical member, the cylindrical member is made of a metal material, prior And a voltage applied to the terminal member is applied to the cylindrical member via the voltage applying member.

Further, the biasing means is a tongue piece member that is formed integrally with the insertion body and has flexibility in the radial direction, and the locking projection is formed at a tip portion of the tongue piece member. It is characterized by being.
Furthermore, the insert is cylindrical, and the tongue piece member is formed by an inner portion of a U-shaped slit formed on the peripheral surface of the insert.

In addition, the engagement holes are plural, and they are formed at equal intervals in the circumferential direction .

  Further, a developing device having a developing sleeve covering the magnet roller is provided, and the cylindrical member is the developing sleeve.

According to the image forming apparatus having the above-described configuration, the external gear is extrapolated to the cylindrical member, and the engagement protrusion is formed in a state where the through hole formed in the cylindrical member and the engagement hole formed in the external gear overlap. The external gear can be easily locked to the cylindrical member by a simple operation of inserting the insert until the overlapped through hole and the engagement hole are positioned.
Moreover, since the latching protrusion engages with the engagement hole through the through hole from the inside of the cylindrical member, it can be configured such that the protrusion does not exist on the outer peripheral side of the cylindrical member as much as possible.

  Furthermore, since it is configured to engage the engaging protrusion formed in the external gear through the through hole formed in the cylindrical member and transmit the power, the power is transmitted to a thin screw as in Patent Document 1. However, the diameter of the locking projection is not limited by the thickness of the developing sleeve, so that the locking projection can be sufficiently thick with respect to the thickness. As a result, transmission of rotational power can be maintained over a longer period.

FIG. 2 is a diagram illustrating a schematic configuration of a tandem printer. It is sectional drawing of the image formation unit with which the said tandem type printer is provided. It is a perspective view of the developing unit provided in the image forming unit. (A) is a perspective view of the side end part to which the external gear with a boss is attached in the developing sleeve in the developing unit, and (b) is a longitudinal sectional view of the end part. It is a disassembled perspective view of a developing sleeve, an external gear with a boss, and a locking member. (A) is the longitudinal cross-sectional view of the edge part by the side to which the external gear with a boss was attached in the developing sleeve of Embodiment 2, (b) is a perspective view of a terminal member. 6 is a perspective view of a state in which a voltage application member is attached to a locking member in Embodiment 2. FIG. FIG. 6 is an exploded perspective view of the locking member and voltage application member of the second embodiment. (A) is a perspective view of the locking member in Embodiment 3, (b) is the cross-sectional view which cut | disconnected the locking member by the plane P in Fig.9 (a). It is a figure for demonstrating a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Embodiment 1>
FIG. 1 is a diagram illustrating a schematic configuration of a tandem type printer 10 (hereinafter simply referred to as “printer 10”) according to an embodiment. In addition, the scale of a structural member is not unified in all the figures including this figure.

  As shown in FIG. 1, the printer 10 includes a transfer belt 14 that is horizontally installed in the housing 12 and travels in the direction of arrow A, and four image forming units 16 </ b> C that are arranged in the travel direction of the transfer belt 14. 16M, 16Y, 16K, primary transfer rollers 18C, 18M, 18Y, 18K provided corresponding to the respective image forming units, and a secondary transfer unit 20, and each image forming unit 16C, 16M, 16Y, 16K. This is a so-called intermediate transfer type image forming apparatus in which the formed toner images of the respective color components are once transferred onto the transfer belt 14 and then transferred to the recording sheet S to form a color image.

Each of the image forming units 16C, 16M, 16Y, and 16K has charging units 24C, 2M, 24Y, and 24K arranged around the photosensitive drums 22C, 22M, 22Y, and 22K as image carriers, and a developing unit. 26C, 26M, 26Y, and 26K.
An exposure unit 28 is disposed below the image forming units 16C,..., 16K, and light-modulated laser beams LB are emitted toward the respective photosensitive drums 22C,.

  The surfaces of the photosensitive drums 22C,..., 22K rotated in the direction of arrow B are uniformly charged by the charging units 24C,. A latent image is formed, and the electrostatic latent image is developed into a toner image (development) by the developing units 26C,. Each of the developing units 26C,..., 26K is sensitive to toners of C (cyan), M (magenta), Y (yellow), and K (black) corresponding to the light modulation color component of the laser light. Supplied to body drums 22C,.

The toner images formed on the photosensitive drums 22C,..., 22K travel by receiving the action of an electric field generated between the primary transfer rollers 18C,..., 18K and the photosensitive drums 22C,. The images are sequentially transferred onto the transfer belt 14.
On the other hand, the recording sheet S fed from the paper feed cassette 30 by the pickup roller 32 is moved to the secondary transfer unit 20 by the registration roller 34 in accordance with the timing when the toner image on the transfer belt 14 reaches the secondary transfer unit 20. It is conveyed. The secondary transfer unit 20 transfers the toner image superimposed on the transfer belt 14 onto the recording sheet S.

  The recording sheet to which the toner image is transferred is conveyed to the fixing device 36. The fixing device 36 includes a fixing roller 38 that is a cylindrical member and a pressure roller 40 that is a pressing member. A heater lamp 42 as a heat source is built in the hollow portion of the fixing roller 38, and the fixing roller 38 is rotated in the direction of arrow F by rotational power transmitted from a motor (not shown) via a power transmission mechanism (not shown). To be rotated. The pressure roller 40 is formed by forming an elastic layer made of silicone rubber or fluororesin on a metal cored bar outer peripheral surface. The pressure roller 40 is in pressure contact with the fixing roller 38 by a pressure contact mechanism (not shown). Due to the pressure contact, a fixing nip is formed between the rollers 38 and 40, and the pressure roller 40 rotates as the fixing roller 38 rotates. The recording sheet carrying the unfixed toner image is passed through the fixing nip, and the toner image is fixed on the recording sheet S.

The recording sheet S on which the toner image is fixed is discharged to a discharge tray 46 by a discharge roller 44.
FIG. 2 is a sectional view of the image forming unit. Note that each of the four image forming units 16C, 16M, 16Y, and 16K provided for each color has the same configuration. Therefore, in the following description and the drawings used for this, C, M, Y , K is omitted.

As described above, the image forming unit 16 is provided with the charging unit 24 and the developing unit 26 around the photosensitive drum 22 that is a cylindrical member.
The developing unit 26 is a unit type developing device. The developing unit 26 includes a developing container 48 for storing a two-component developer (hereinafter simply referred to as “developer”, not shown in FIG. 2) composed of toner and a magnetic carrier.

  The developing unit 26 also includes a developing sleeve 50 that is a cylindrical member provided so that a part of the outer periphery is exposed from the developing container 48. The developing sleeve 50 is disposed in parallel with the photosensitive drum 22 so as to face the photosensitive drum 22 with a predetermined interval (developing gap). The predetermined interval is, for example, 0.3 [mm]. The developing sleeve 50 is made of a nonmagnetic material such as aluminum or austenitic stainless steel, and has a thickness of 0.5 [mm].

In the hollow portion of the developing sleeve 50, a cylindrical magnet roller 54 that is integrally attached to the shaft 52 is provided. In other words, the developing sleeve 50 covers the magnet roller 54. The shaft 52 is fixed so as not to rotate. The magnet roller 54 is a magnet body having a plurality of magnetic poles in the circumferential direction.
A first screw feeder 56 and a second screw feeder 58 for stirring the developer and transporting the developer to the developing sleeve 50 are provided in the developing container 48 below the developing sleeve 50.

  The carrier which is agitated and frictionally charged by the first and second screw feeders 56 and 58 and has the toner adhered thereto is magnetically attracted to the surface of the developing sleeve 50. A magnetically attracted brush-like developer (not shown) is conveyed by the developing sleeve 50 rotated in the direction of arrow E, and the conveyance amount is regulated by the head height regulating plate 60 in the middle. The electrostatic latent image formed on the surface of the photosensitive drum 22 is developed by being conveyed to a region (developing region) facing the surface of the drum 22. The remaining developer after the development is collected in the developing container 48 by the rotating developing sleeve 50.

FIG. 3 is a perspective view of the developing unit 26. FIG. 3 is a view of the developing unit 26 as viewed from the direction in which the photosensitive drum 22 exists, and is a view in which the developing sleeve 50 exposed from the developing container 48 appears.
The developing sleeve 50 is rotatably supported by slide bearings 62 and 64 provided at both ends. The slide bearings 62 and 64 are fixed to the frame 66 of the developing unit 26. Note that a strip-shaped metal piece (not shown) is in sliding contact with the outer peripheral surface of the end portion of the developing sleeve 50 that is supported by the slide bearing 64, and the developing sleeve 50 is in contact with the developing sleeve 50 via the metal piece. A developing bias voltage is applied.

  In the developing sleeve 50, a boss-equipped external gear 68 is attached in an externally fitted state adjacent to the sliding bearing 62 at a portion closer to the center than the sliding bearing 62 on the end portion supported by the sliding bearing 62 ( Extrapolated.) In addition, a docking gear 70 formed of an external gear that meshes with the external gear 68 with a boss is rotatably attached to the frame 66. A main body gear (not shown) made of an external gear that meshes with the docking gear 70 in a state where the developing unit 26 is mounted on the main body of the printer 10 is provided on the main body side. Rotational power is transmitted from a certain motor (not shown). The rotational power is transmitted to the developing sleeve 50 via the main body external gear, the docking gear 70, the external gear 68 with a boss, and a locking member 72 (not shown in FIG. 3) to be described later. Will be rotated.

  A locking member 72 that is a locking means for locking the external gear 68 with the boss to the developing sleeve 50 will be described with reference to FIGS. 4 and 5. 4A is a perspective view of a side end portion of the developing sleeve 50 to which the external gear 68 with a boss is attached, and FIG. 4B is a longitudinal sectional view of the end portion. FIG. 5 is an exploded perspective view of the developing sleeve 50, the external gear 68 with a boss, and the locking member 72. In FIG. 4A, the shaft 52 (FIGS. 2 and 4B) protruding in the axial direction from the slide bearing 62 is omitted.

  As shown in FIG. 5, the boss-equipped external gear 68 includes a gear portion 74 and a first boss portion 76 and a second boss portion 78 extending in the axial direction from both sides of the gear portion 74. The gear part 74 consists of a helical gear. The first boss portion 76 is provided with an engagement hole 76A that is a through hole that penetrates in the radial direction. Further, another engagement hole 76B is opened at a position 180 degrees in the circumferential direction from the engagement hole 76A (FIG. 4B). The inner diameter of the shaft hole of the external gear 68 with the boss is set to a size that allows the developing sleeve 50 to be smoothly inserted without rattling (a size that allows the developing sleeve 50 to be smoothly inserted without rattling).

As shown in FIG. 5, the developing sleeve 50 is also provided with a through hole 50 </ b> A that penetrates in the radial direction. Further, another through hole 50B (FIG. 4B) is opened at a position 180 degrees in the circumferential direction from the through hole 50A. The diameters of the through holes 50A and 50B and the engagement holes 76A and 76B are the same.
The locking member 72 has a form that is basically formed by cutting a part of a cylindrical member (in this example, a cylindrical member). The locking member 72 is made of synthetic resin.

  As shown in FIG. 5, the locking member 72 has a vertically long “U” -shaped slit formed in a cylindrical member (hereinafter referred to as “cylindrical member”). A strip-shaped tongue member 82 is created. That is, the tongue piece member 82 includes an inner portion of the “U” -shaped slit. Here, a portion other than the tongue piece member and a locking projection described later is referred to as a main body portion 80.

In other words, the tongue piece member 82 is formed integrally with the main body portion 80, extends in parallel with the axial center of the tubular member from the main body portion 80, and extends in the radial direction from the base end portion of the extension to the distal end portion. It has the flexibility to bend. At the distal end portion of the tongue piece member 82, a locking projection 84 made of a columnar (in this example, columnar) projection is provided.
Similarly, a tongue piece member 86 is formed at a position 180 degrees in the circumferential direction from the tongue piece member 82, and a locking projection 88 is similarly provided at the tip of the tongue piece member 86. (FIG. 4B).

The main body 80 has a cylindrical surface 80A, and the outer diameter of the cylindrical surface 80A is set to a size that allows the main body 80 to be smoothly inserted into the developing sleeve 50 without rattling. The main body 80 functions as an insertion body inserted into the developing sleeve 50 with the tongue piece members 82 and 86 and the locking projections 84 and 88.
Next, an assembly procedure of the developing sleeve 50, the external gear 68 with the boss, and the locking member 72 having the above-described configuration will be described.

First, after the boss-equipped external gear 68 is extrapolated to the developing sleeve 50 in the direction of the arrow G shown in FIG. 5, the through hole 50A and the engaging hole 76A, and the through hole 50B and the engaging hole 76B (FIG. 4B). ) So as to communicate with each other, the boss-equipped external gear 68 and the developing sleeve 50 are relatively aligned.
The positions where the through holes 50A and the engaging holes 76A, and the through holes 50B and the engaging holes 76B (FIG. 4B) communicate with each other are defined positions of the external gear 68 with boss with respect to the developing sleeve 50. In other words, the through holes 50 </ b> A and 50 </ b> B are formed at positions where the boss-equipped external gear 68 is overlapped with the engagement holes 76 </ b> A and 76 </ b> B in a state where the external gear 68 with the boss is attached to the specified position of the developing sleeve 50. The specified position refers to a state in which the external gear 68 with boss is attached to the developing sleeve 50, and there is a margin for fitting a sliding bearing 62 described later at the end of the developing sleeve 50, and the sliding bearing 62 is attached to the developing sleeve 50. A position where no unnecessary gap is left between the plain bearing 62 and the external gear 68 with the boss in the fitted state.

When the alignment is performed, the locking member 72 is inserted into the developing sleeve 50 in which the external gear 68 with the boss is fitted in the direction of the arrow H shown in FIG. At this time, the locking protrusions 84 and 88 are pushed so as to approach each other (the tongue piece members 82 and 86 are elastically deformed and bent inward in the radial direction) and are embedded in the developing sleeve 50.
Further, the developing sleeve 50 is moved until the locking protrusions 84 and 88 reach the position of the communicating through hole 50A and the engaging hole 76A, and the communicating through hole 50B and the engaging hole 76B, respectively. Go further into the back. When each of the locking projections 84 and 88 reaches the position of the communicating through holes 50A and 50B, the locking projections 84 and 88 are respectively connected to the through holes 50A and 50B by the restoring force of the tongue piece members 82 and 86. Through the engagement holes 76A and 76B. As a result, as shown in FIG. 4B, the external gear 68 with boss is locked to the developing sleeve 50 by the locking member 72 inserted into the developing sleeve 50.

As described above, according to the above-described embodiment, with the boss-attached external gear 68 positioned in the developing sleeve 50, the engaging member 72 can be inserted into the developing sleeve 50 with a simple operation. The external gear 68 can be locked to the developing sleeve 50.
Further, since the locking projections 84 and 88 enter the through hole 50A and the engaging hole 76A and the through hole 50B and the engaging hole 76B, respectively, from the inside of the developing sleeve 50, the outer periphery of the boss portion 76 (where possible) A configuration in which no protrusion exists on the outer peripheral side of the developing sleeve 50 can be adopted. In the example shown in FIG. 4B, the locking projections 84 and 88 protrude from the opening edges of the engagement holes 76A and 76B by the chamfered end portions, but the end surfaces of the locking projections 84 and 88 are engaged. You may set the height of the latching protrusions 84 and 88 so that it may align with the opening edge of the joint holes 76A and 76B.

The end portion of the developing sleeve 50 to which the external gear 68 with boss is locked is rotatably supported by a slide bearing 62.
The slide bearing 62 is made of a synthetic resin such as polyacetal. As shown in FIGS. 4A and 4B, the slide bearing 62 has a double cylindrical shape, and one end portion of the developing sleeve 50 is inserted into and supported by the outer cylindrical portion 62A. Further, one end portion of the shaft 52 is inserted into and supported by the inner cylindrical portion 62B.

The slide bearing 62 has a pair of attachment pieces 62C and 62D extending radially outward from the cylindrical portion 62A. Each of the attachment pieces 62C and 62D has attachment holes 62E and 62F formed of through holes. Has been established. The slide bearing 62 is fixed to the frame 66 (FIG. 3) with screws (not shown) through the mounting holes 62E and 62F.
Note that another slide bearing 64 (FIG. 3) that pivotally supports the developing sleeve 50 has the same configuration as the slide bearing 62 and the same support mode, and therefore illustration and description thereof are omitted.

In the developing sleeve 50 in which the external gear 68 with boss is locked and rotatably supported by the slide bearings 62 and 64, the rotational power of the external gear 68 with boss is supplied to the developing sleeve 50 via the locking projections 84 and 88. Is transmitted to. In the present embodiment, since the engaging projection is fitted into the hole formed in each of the external gear with the boss and the developing sleeve to transmit the power, it is limited to a thin screw as in Patent Document 1. First, since the diameter of the locking projection is almost not limited by the thickness of the developing sleeve, the locking projection can be made sufficiently thick with respect to the thickness. As a result, transmission of rotational power can be maintained over a long period.
<Embodiment 2>
In the first embodiment, a metal piece (not shown) is brought into sliding contact with the outer peripheral surface of the developing sleeve 50, and a developing bias voltage is applied to the developing sleeve 50 via the metal piece. On the other hand, in the second embodiment, a developing bias voltage is applied by bringing a metal member into contact with the inner peripheral surface of the developing sleeve 50.

The second embodiment will be described with reference to FIGS. 6 to 8, the same or substantially the same components as those of the first embodiment are denoted by the same reference numerals, and are only referred to as necessary.
FIG. 6A is a longitudinal sectional view of the end portion of the developing sleeve 50 on the side where the external gear 68 with boss is attached. In FIG. 4B shown in the first embodiment, the end portion is cut along a plane including the locking projections 84 and 88 of the locking member. However, in FIG. It is cut by the plane to be. In FIG. 6A, the shaft 52 and the magnet roller 54 (FIG. 4B) are omitted. FIG. 6B is a perspective view of the terminal member 100 described later. FIG. 7 is a perspective view of a state in which a voltage applying member 90 described later is attached to the locking member 96, and FIG. 8 is an exploded perspective view of the locking member 96 and the voltage applying member 90.

As shown in FIG. 8, the voltage application member 90 is formed by bending a metal (for example, stainless steel) strand, and is a compression coil spring portion 92 (hereinafter simply referred to as “coil spring portion 92”). And a contact portion 94 formed by extending the element wire from the coil spring portion 92.
The contact portion 94 extends in a direction parallel to the axial center of the compression coil spring portion 92, and in the middle of the contact portion 94, it protrudes toward the outside in the direction parallel to the radial direction of the coil spring portion 92. It is bent in a letter shape.

One end of the main body 98 of the locking member 96 is formed with a small diameter portion 96B into which one end of the coil spring portion 92 (the end on the side where the contact portion 94 is extended) is fitted. In addition, a groove portion 98 </ b> A extending in a direction parallel to the axial direction is formed on the outer peripheral surface of the main body portion 98.
As shown in FIG. 7, the voltage applying member 90 is assembled to the locking member 96 by partially embedding the contact portion 94 in the groove portion 98 </ b> A and fitting one end portion of the coil spring portion 92 in the small diameter portion 96 </ b> B. It has been.

As shown in FIG. 6, the assembly of the locking member 96 and the voltage application member 90 (FIG. 7) has a locking projection from the locking member 96 side on the developing sleeve 50 in which the external gear 68 with a boss is inserted. 84 and 88 (FIG. 7) are inserted to the positions where they enter the through hole 50A-engaging hole 76A and the through hole 50B-engaging hole 76B (not shown in FIG. 6), respectively.
When the insertion is completed, the contact portion 94 bent in a “<” shape is pressed by the inner peripheral surface of the developing sleeve 50 and elastically deformed so that the “<” shape is opened. The bending point portion 94 </ b> A is in contact (pressure contact) with the inner peripheral surface of the developing sleeve 50. Thereby, the electrical connection between the voltage applying member 90 and the developing sleeve 50 is achieved.

As shown in FIG. 6A, the end portion of the developing sleeve 50 is rotatably supported by a slide bearing 620, as in the first embodiment. The slide bearing 620 has the same configuration as the slide bearing 62 of the first embodiment except that a later-described extraction hole 620B is opened. That is, it has a double cylindrical shape having a cylindrical portion 62A and a cylindrical portion 62B.
A terminal member 100 formed of a metal material (for example, stainless steel) is provided on a bottom portion 620A between the outer cylindrical portion 62A and the inner cylindrical portion 62B. As shown in FIG. 6B, the terminal member 100 includes an annular plate-like portion 100A, and a strip piece portion 100B extending perpendicularly from the outer periphery of the plate-like portion 100A to the main surface of the plate-like portion 100A. Consists of. In the terminal member 100, a plate-like portion 100A is provided on the bottom portion 620A, a strip piece portion 100B is drawn out through a lead-out hole 620B formed in the bottom portion 620A, and a part thereof is exposed to the outside from the slide bearing 620. ing.

  The coil spring portion 92 of the voltage application member 90 is inserted in a compressed state between the main body portion 98 of the locking member 96 and the plate-like portion 100A of the terminal member 100, and by the restoring force of the coil spring portion 92, The plate-like portion 100A side end of the coil spring portion 92 and the plate-like portion 100A are always kept in contact with each other. Thereby, the electrical connection between the coil spring portion 92 and the plate-like portion 100A (terminal member 100) is achieved.

In the above configuration, when a voltage is applied to the portion (exposed portion) exposed from the slide bearing 620 of the strip piece portion 100B in the terminal member 100, the plate portion 100A, the coil spring portion 92, and the contact portion 94 are used. A voltage is applied to the developing sleeve 10.
Since the voltage application member 90 is partially embedded in the groove portion 98A of the locking member 96, the voltage applying member 90 rotates integrally with the locking member 96 when the developing sleeve 50 is rotated. In this case, the plate-like portion 100A side end of the coil spring portion 92 slides with respect to the stationary plate-like portion 100A. For this reason, in order to further widen the sliding contact surface of the coil spring portion 92 with the plate-like portion 100A, it is preferable that the end portion of the coil spring portion 92 is a closed end and has a ground finish. Finish).

In addition, the winding direction of the coil spring portion 92 is preferably set to a direction in which the sliding resistance received from the plate-like portion 100A during the rotation acts to reduce the diameter of the coil spring portion 92.
According to the second embodiment, since the voltage applying member is in contact with the inner peripheral surface of the developing sleeve 50, the total length of the developing sleeve 50 can be shortened as compared with the case in which the voltage applying member is in contact with the outer peripheral surface. As a result, the developing device can be further downsized.

That is, when the strip-shaped metal piece is in contact with the outer peripheral surface as in the first embodiment, it is necessary to provide the metal piece on the outer side in the longitudinal direction of the photosensitive drum disposed to face the developing sleeve 50. This is because the developing sleeve becomes longer by the installation space of the metal piece, but there is no such restriction when it is provided on the inner peripheral surface of the developing sleeve 50.
<Embodiment 3>
The third embodiment is basically the same as the first and second embodiments except that the configuration of the locking member for locking the external gear 68 with boss to the developing sleeve 50 is different.

Therefore, it demonstrates centering on a locking member. FIG. 9A is a perspective view of the locking member 102 according to the third embodiment.
Like the locking member 72 (FIG. 5), the locking member 102 is basically a part of a cylindrical member (in this example, a cylindrical member, hereinafter referred to as a “cylindrical member”). Is in the form of being cut out. The locking member 102 is also made of synthetic resin.

  In the locking member 72, the tongue piece members 82 and 86 are formed in the longitudinal direction (length direction) of the cylindrical member. However, in the locking member 102, as shown in FIG. It is formed in the circumferential direction. The tongue piece member 104 is created by a “U” -shaped slit 112 formed in the tubular member. A locking protrusion 106 having a columnar shape (in this example, a columnar shape) is provided at the distal end portion of the tongue piece member 104. Here, also in the present embodiment, a portion other than the tongue piece member and the locking projection is referred to as a main body portion 114.

In other words, the tongue piece member 104 is formed integrally with the main body portion 114, extends from the main body portion 114 in the circumferential direction of the cylindrical member, and is at least cylindrical from the extended base end portion to the distal end portion. It has the flexibility to bend inside the member.
FIG. 9B shows a cross-sectional view taken along the plane P in FIG. As shown in FIG. 9B, a tongue piece member 108 is similarly formed on the opposite side of the tongue piece member 104, and a locking projection 110 is provided at the tip of the tongue piece member 108. Yes.

  Returning to FIG. 9A, the main body 114 has a cylindrical surface 114A, and the outer diameter of the cylindrical surface 114A can be smoothly inserted into the developing sleeve 50 (FIGS. 4 and 5) without rattling of the main body 114. Set to size. The main body 114 functions as an insertion body inserted into the developing sleeve 50 with the tongue pieces 104 and 108 and the locking projections 106 and 110 as in the case of the first embodiment.

Since the assembly procedure of the developing sleeve 50, the external gear 68 with the boss (FIG. 5), and the locking member 104 is the same as that of the first embodiment, the description thereof is omitted.
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described form, and for example, the following form may be adopted.
(1) The engagement hole provided in the external gear with the boss is not limited to the through hole as in the above embodiment, and may be a bottomed hole. In short, it may be formed on the inner peripheral surface of the shaft hole of the external gear with boss so as to be engaged with the locking projection.

(2) In the above embodiment, the external gear with a boss is used as the gear that is engaged with the developing sleeve and transmits the power, but an external gear that does not have a boss may be used. Moreover, in the said embodiment, although the helical gear was used as the said external gear, not only this but a spur gear may be used.
(3) In the above embodiment, the external gear is locked to the developing sleeve by two locking protrusions, but the number of locking protrusions may be one. Alternatively, three or more may be used. When using a plurality, it is preferable to provide them at equal intervals in the circumferential direction of the external gear and the developing sleeve. In other words, it is preferable to provide rotational symmetry about the axis of the developing sleeve.

  (4) The tongue piece member is used as the urging means for urging the locking projection outward of the developing sleeve. However, the present invention is not limited to this, and a compression coil spring may be used as the urging means. A cylindrical recess is provided on the outer periphery of the insertion body. The compression coil spring is embedded in the recess, and a columnar locking projection is formed on the upper end of the compression coil spring. You may make it arrange | position so that it may be exposed from. In this case, an elastic member such as a sponge may be used instead of the compression coil spring.

(5) In the above-described embodiment, the developing sleeve is described as an example of the cylindrical member that is driven to rotate by locking the external gear. However, the cylindrical member is not limited to the developing sleeve, and may be a fixing roller used in the fixing device. You may apply. Alternatively, it can be applied to a photosensitive drum.
(6) In the above embodiment, the printer has been described as an example. However, the image forming apparatus according to the present invention is not limited to the printer, but other image forming apparatuses such as a copying machine, a facsimile, or a multifunction machine having these functions. It is applicable to.

  The present invention can be suitably used for an image forming apparatus such as a printer or a copier having a cylindrical member such as a developing sleeve.

DESCRIPTION OF SYMBOLS 10 Tandem type printer 50 Development sleeve 50A, 50B Through-hole 68 Bossed external gear 72, 96, 102 Locking member 76A, 76B Engagement hole 80, 98, 114 Body part 82, 86, 104, 108 Tongue piece member 84, 88,106,110 Locking projection

Claims (5)

The extrapolated external gear on the outer circumference of the cylindrical member engaged with the engaging means, the image forming having a structure for rotating said cylindrical member to transmit rotational force from a drive source is transmitted to the cylindrical member via said external gear A device,
At least one engagement hole is formed on the inner peripheral surface of the shaft hole of the external gear,
Wherein the cylindrical member has the external gear is through hole is formed overlapping with the engaging hole of the external gear while being attached to the predetermined position of the cylindrical member,
The locking means is
An insert inserted into the cylindrical member;
A locking projection;
An urging means for urging the locking protrusion against the insertion body in the radially outward direction of the cylindrical member;
With
The configuration for rotationally driving the cylindrical member is:
A sliding bearing member made of a synthetic resin having a bottomed cylindrical shape, which is extrapolated to an end of the cylindrical member and rotatably holds the cylindrical member;
A terminal member including a plate-like portion provided at a bottom portion of the plain bearing member, and an exposed piece portion extending from the plate-like portion and exposed to the outside of the cylindrical member;
A coil spring portion interposed between the insert and the plate-like portion in a compressed state and having one end slidingly contacted with the plate-like portion, and a wire of the coil spring portion extending from the other end of the coil spring portion. A voltage applying member comprising a contact portion elastically contacting the inner peripheral surface of the cylindrical member,
With
When interpolating said insert into said cylindrical member, said locking projection which is biased by the biasing means, through the through hole of the cylindrical member, engaged with the engagement hole of the external gear By combining, the external gear is configured to be locked to the cylindrical member ,
The image forming apparatus, wherein the cylindrical member is made of a metal material, and a voltage applied to the terminal member is applied to the cylindrical member via the voltage applying member .   The biasing means is a tongue piece member that is formed integrally with the insert and has flexibility in the radial direction, and the locking protrusion is formed at the tip of the tongue piece member. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 2, wherein the insert has a cylindrical shape, and the tongue piece member includes an inner portion of a U-shaped slit formed on a peripheral surface of the insert. .   The image forming apparatus according to claim 1, wherein a plurality of the engagement holes are formed at equal intervals in the circumferential direction. A developing device having a developing sleeve covering the magnet roller;
The image forming apparatus according to claim 1 , wherein the cylindrical member is the developing sleeve.

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